Compressed System Information for Link Budget Limited UEs in a Radio Access Network

ABSTRACT

Techniques are disclosed relating to broadcasting and receiving system information in a radio access network (RAN). In some embodiment, a base station is configured to broadcast different sets of first system information blocks (SIBs) for different classes of user equipment devices (e.g., traditional UEs and UEs having a limited link budget). Different classes of UEs may use the different sets of SIBs to initiate communications with the base station

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.15/846,524, filed Dec. 19, 2017; which is a continuation of U.S. patentapplication Ser. No. 14/865,395, filed Sep. 25, 2015; which claims thebenefit of U.S. Provisional Application No. 62/083,075, filed on Nov.21, 2014, each of which are incorporated by reference herein in theirrespective entireties.

The claims in the instant application are different than those of theparent application or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication or any predecessor application in relation to the instantapplication. The Examiner is therefore advised that any such previousdisclaimer and the cited references that it was made to avoid, may needto be revisited. Further, any disclaimer made in the instant applicationshould not be read into or against the parent application or otherrelated applications.

FIELD OF THE INVENTION

The present application relates to wireless cellular devices, and moreparticularly to techniques for broadcasting and receiving systeminformation.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further,wireless communication technology has evolved from voice-onlycommunications to also include the transmission of data, such asInternet and multimedia content.

Wireless base stations typically broadcast system information (SI) inmessages that are repeated periodically. UEs may use acquired SI forcell selection, cell reselection, and before initiating communicationwith a given base station. Each SI message includes one or more systeminformation blocks (SIBs). For example, in some LTE networks, an eNBbroadcasts a master information block (MIB) on the physical broadcastchannel (PBCH) and other SIBs on the physical download shared channel(PDSCH) through radio resource control (RRC) messages. Examples ofsystem information included in the SIBs include: random access channel(RACH) configuration, uplink frequency and bandwidth, pagingconfiguration, cell selection/reselection information, neighbor cellinformation, etc.

Some UEs with limited link budgets may not be able to reliably decode SImessages when they are broadcast at typical coding-rates and transportblock (TB) sizes used by a base station. For example, bundling ofmultiple SIBs on a given SI window may lead to large TB sizes that aredifficult to decode.

The “link budget” of a UE refers to an accounting of gains and lossesfrom a transmitter, through the communications medium, and to areceiver. The link budget may be based on communication configuration(e.g., sub-channel and subframe spacing and bandwidth, number ofantennas used, modulation type, etc.), transmitter parameters (e.g.,power, antenna gain, filter/cable loss, etc.), receiver parameters(noise, antenna gain, filter/cable loss, etc.) and other parameters(e.g., handoff gain, HARQ gain, coding gain, penetration loss, etc.).

Therefore, improvements are desired in wireless communication in thecontext of UEs with limited link budgets.

SUMMARY OF THE INVENTION

Embodiments described herein may relate to broadcasting and receivingsystem information in a radio access network (RAN).

In some embodiments, a base station includes at least one antenna, atleast one radio, configured to perform cellular communication using aradio access technology (RAT), and one or more processors coupled to theradio. In these embodiments, the base station is configured to broadcastfirst system information blocks (SIBs) encoded using a first coding rateand a first identifier. In these embodiments, the base station is alsoconfigured to broadcast second SIBs encoded using a second coding ratethat is lower than the first coding rate and a second identifier. Inthese embodiments, the second SIBs include only a portion of theinformation included in the first SIBs and the second SIBs are usable bya class of user equipment devices (UEs) having a limited link budget todetermine access parameters for the base station.

In some embodiments, a user equipment device (UE) includes at least oneantenna, at least one radio configured to perform cellular communicationusing a radio access technology (RAT), and one or more processorscoupled to the radio. In these embodiments, the one or more processorsand the radio are configured to perform voice and/or datacommunications. In these embodiments, the UE is configured to receivecompressed system information blocks (SIBs) in a broadcast transmissionfrom a base station. In this embodiment, the base station is configuredto broadcast transmissions with both compressed SIBs and non-compressedSIBs. In these embodiments, the UE is configured to decode thecompressed SIBs from the broadcast transmission and initiatecommunication with the base station based on access parameters specifiedby the decoded compressed system information.

In some embodiments, an apparatus includes one or more processingelements configured to decode compressed SIBs from a broadcasttransmission from a base station, wherein the base station is configuredto broadcast transmissions with both compressed SIBs and non-compressedSIBs. In some embodiments, the one or more processing elements areconfigured to initiate communication with the base station based onaccess parameters specified by the decoded compressed systeminformation. The apparatus may consist of the one or more processingelements and/or may be an integrated circuit.

In some embodiments, a method includes a base station broadcasting firstsystem information blocks (SIBs) encoded using a first coding rate and afirst identifier broadcasting second SIBs encoded using a second codingrate that is lower than the first coding rate and a second identifier.In these embodiments, the second SIBs include only a portion of theinformation included in the first SIBs and the second SIBs are usable bya class of user equipment devices (UEs) having a limited link budget todetermine access parameters for the base station.

In some embodiments, a method includes a user equipment device (UE)receiving compressed system information blocks (SIBs) in a broadcasttransmission from a base station, decoding the compressed SIBs from thebroadcast transmission, and initiating communication with the basestation based on access parameters specified by the decoded compressedsystem information.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present disclosure can be obtained whenthe following detailed description of the embodiments is considered inconjunction with the following drawings.

FIG. 1 illustrates an exemplary wireless communication system, accordingto some embodiments.

FIG. 2 illustrates a base station in communication with a user equipmentdevice, according to some embodiments.

FIG. 3 illustrates a user equipment device in communication with anetwork via a base station, according to some embodiments.

FIG. 4 is an example block diagram of a user equipment device, accordingto some embodiments.

FIG. 5 is an example block diagram of a base station, according to someembodiments.

FIGS. 6A-11 illustrate exemplary information included in compressedSIBs, according to some embodiments.

FIG. 12 illustrates an exemplary method for broadcasting compressedSIBs, according to some embodiments.

FIG. 13 illustrates an exemplary method for receiving compressed SIBs,according to some embodiments.

While the disclosure is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to limit the disclosure to the particular formdisclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the present disclosure as defined by the appended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS

This disclosure initially describes, with reference to FIGS. 1-5, anoverview of exemplary embodiments of a radio access network, UE device,and base station. FIGS. 6A-11 show exemplary information included incompressed SIBs, which may be broadcast for a class of UE devices havinglimited link budgets. FIGS. 12-13 illustrate exemplary embodiments ofmethods for broadcasting/receiving compressed SIBs. In some embodiments,the compressed system information may allow lower coding rates and/orsmaller transport blocks for link budget limited devices relative tosystem information for other devices. In some embodiments, the disclosedtechniques may facilitate decoding of system information by UE deviceswith limited link budgets.

Acronyms

The following acronyms may be used in the present Provisional PatentApplication:

3GPP: Third Generation Partnership Project

3GPP2: Third Generation Partnership Project 2

APN: Access Point Name

BLER: Block Error Rate (same as Packet Error Rate)

BER: Bit Error Rate

CRC: Cyclic Redundancy Check

DL: Downlink

GBR: Guaranteed Bit Rate

GSM: Global System for Mobile Communications

IMS: IP Multimedia Subsystem

IP: Internet Protocol

LTE: Long Term Evolution

MIB: Master Information Block

MME: Mobility Management Entity

MO: Message Originating

MT: Message Terminating

NAS: Non-access Stratum

PCC: Policy and Charging Control

PCEF: Policy and Charging Enforcement Function

PCRF: Policy and Charging Rules Function

PCSCF: Proxy Call Session Control Function

PDSCH: Physical Downlink Shared Channel

PDCCH: Physical Downlink Control Channel

PER: Packet Error Rate

PGW: Packet Gateway

PUSCH: Physical Uplink Shared Channel

QCI: Quality of Service Class Index

QoS: Quality of Service

RACH: Random Access Procedure

RNTI: Radio Network Temporary Identifier

RRC: Radio Resource Control

SGW: Serving Gateway

SINR: Signal to Interference-and-Noise Ratio

SIR: Signal to Interference Ratio

SNR: Signal to Noise Ratio

TB: Transport Block

Tx: Transmission

SI: System Information

SIB: System Information Block

UE: User Equipment

UL: Uplink

UMTS: Universal Mobile Telecommunication System

VoLTE: Voice Over LTE

Terms

The following is a glossary of terms used in the present application:

Memory Medium—Any of various types of memory devices or storage devices.The term “memory medium” is intended to include an installation medium,e.g., a CD-ROM, floppy disks, or tape device; a computer system memoryor random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, RambusRAM, etc.; a non-volatile memory such as a Flash, magnetic media, e.g.,a hard drive, or optical storage; registers, or other similar types ofmemory elements, etc. The memory medium may include other types ofmemory as well or combinations thereof. In addition, the memory mediummay be located in a first computer system in which the programs areexecuted, or may be located in a second different computer system whichconnects to the first computer system over a network, such as theInternet. In the latter instance, the second computer system may provideprogram instructions to the first computer for execution. The term“memory medium” may include two or more memory mediums which may residein different locations, e.g., in different computer systems that areconnected over a network. The memory medium may store programinstructions (e.g., embodied as computer programs) that may be executedby one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), personal communication device, smart phone, wearabledevice, television system, grid computing system, or other device orcombinations of devices. In general, the term “computer system” can bebroadly defined to encompass any device (or combination of devices)having at least one processor that executes instructions from a memorymedium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which perform wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), wearable devices(e.g., smart watch, smart glasses), portable gaming devices (e.g.,Nintendo DS™, PlayStation Portable™, Gameboy Advance™, iPhone™),laptops, PDAs, portable Internet devices, music players, data storagedevices, or other handheld devices, etc. In general, the term “UE” or“UE device” can be broadly defined to encompass any electronic,computing, and/or telecommunications device (or combination of devices)which is easily transported by a user and capable of wirelesscommunication.

Base Station—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processing Element—refers to various elements or combinations ofelements that are capable of performing a function in a device, such asa user equipment or a cellular network device. Processing elements mayinclude, for example: processors and associated memory, portions orcircuits of individual processor cores, entire processor cores,processor arrays, circuits such as an ASIC (Application SpecificIntegrated Circuit), programmable hardware elements such as a fieldprogrammable gate array (FPGA), as well any of various combinations ofthe above.

Link Budget Limited —includes the full breadth of its ordinary meaning,and at least includes a characteristic of a wireless device (a UE) whichexhibits limited communication capabilities, or limited power, relativeto a device that is not link budget limited, or relative to devices forwhich a radio access technology (RAT) standard has been developed. A UEthat is link budget limited may experience relatively limited receptionand/or transmission capabilities, which may be due to one or morefactors such as device design, device size, battery size, antenna sizeor design, transmit power, receive power, current transmission mediumconditions, and/or other factors. Such devices may be referred to hereinas “link budget limited” (or “link budget constrained”) devices. Adevice may be inherently link budget limited due to its size, batterypower, and/or transmit/receive power. For example, a smart watch that iscommunicating over LTE or LTE-A with a base station may be inherentlylink budget limited due to its reduced transmit/receive power and/orreduced antenna. Alternatively, a device may not be inherently linkbudget limited, e.g., may have sufficient size, battery power, and/ortransmit/receive power for normal communications over LTE or LTE-A, butmay be temporarily link budget limited due to current communicationconditions, e.g., a smart phone being at the edge of a cell, etc. It isnoted that the term “link budget limited” includes or encompasses powerlimitations, and thus a power limited device may be considered a linkbudget limited device.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

FIGS. 1-3—Communication System

FIG. 1 illustrates a simplified communication system where a userequipment (UE) 106 is in communication with a base station 102. The UE106 may be a device with wireless network connectivity such as a mobilephone, a hand-held device, a computer or a tablet, or virtually any typeof wireless device. FIG. 2 illustrates an expanded wirelesscommunication system involving multiple UEs 106A-N, base stations 102Aand 102B, core networks 100A and 100B, and an external network 108.However, it should be noted that the system of FIG. 2 is merely oneexample of a possible system, and embodiments may be implemented in anyof various systems, as desired.

The base stations 102 may be base transceiver stations (BTS) and/or cellsites, and may include hardware that enables wireless communication withthe UEs 106. As shown in FIG. 2, each base station 102 may also beequipped to communicate with a core network 100 (e.g., base station 102Amay be coupled to core network 100A, while base station 102B may becoupled to core network 100B), which may be a core network of a cellularservice provider. Each core network 100 may also be coupled to one ormore external networks (such as external network 108), which may includethe Internet, a Public Switched Telephone Network (PSTN), and/or anyother network, as desired. Thus, the base stations 102 may facilitatecommunication between the user devices 106 and/or between the userdevices 106 and the networks 100A, 100B, and 108.

The base stations 102 and the user devices 106 may be configured tocommunicate over the transmission medium using any of various radioaccess technologies (“RATs”, also referred to as wireless communicationtechnologies) or telecommunication standards such as GSM, UMTS (WCDMA),LTE, LTE Advanced (LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO,HRPD, eHRPD), IEEE 802.11 (WLAN or Wi-Fi), IEEE 802.16 (WiMAX), etc.

Base station 102A and core network 100A may operate according to a firstRAT (e.g., LTE) while base station 102B and core network 100B operateaccording to a second (e.g., different) RAT (e.g., CDMA 2000 or GSM,among other possibilities). The two networks may be controlled by thesame network operator (e.g., cellular service provider or “carrier”), orby different network operators, as desired. In addition, the twonetworks may be operated independently of one another (e.g., if theyoperate according to different cellular communication standards), or maybe operated in a somewhat coupled or tightly coupled manner.

Note also that while two different networks may be used to support twodifferent cellular communication technologies, such as illustrated inthe exemplary network configuration shown in FIG. 2, other networkconfigurations implementing multiple cellular communication technologiesare also possible. As one example, base stations 102A and 102B mightoperate according to different cellular communication technologies butcouple to the same core network. As another example, multi-mode basestations capable of simultaneously supporting different cellularcommunication technologies (e.g., LTE and CDMA2000 1×RTT, LTE and GSM,and/or any other combination of cellular communication technologies)might be coupled to a core network that also supports the differentcellular communication technologies.

The UE 106 may include a processor that is configured to execute programinstructions stored in memory. The UE 106 may perform any of the methodembodiments described herein by executing such stored instructions. TheUE 106 may also or alternatively include a programmable hardware elementsuch as an FPGA (field-programmable gate array) that is configured toperform any of the method embodiments described herein, or any portionof any of the method embodiments described herein.

In some embodiments, the UE 106 may be configured to communicate usingany of multiple wireless communication standards (e.g., 3GPP, 3GPP2,etc.) or multiple RATs. For example, the UE 106 may be configured tocommunicate using two or more of GSM, CDMA2000, LTE, LTE-A, HSPA, WLAN,or GNSS, among other possibilities. In one embodiment, a UE 106 may beconfigured to use a first RAT that is a packet-switched technology(e.g., LTE) and a second RAT that is a circuit-switched technology(e.g., GSM or 1×RTT) while communicating with the base stations 102.Other combinations of RATs are also possible. The UE 106 might also oralternatively be configured to communicate using WLAN, Bluetooth, one ormore global navigational satellite systems (GNSS, e.g., GPS or GLONASS),one and/or more mobile television broadcasting standards (e.g., ATSC-M/Hor DVB-H), etc.

The UE 106 may include one or more antennas for communicating using theRAT(s). In one embodiment, the UE 106 may share one or more parts of areceive and/or transmit chain between multiple RATs; for example, the UE106 might be configured to communicate using either of CDMA2000(1×RTT/1×EV-DO/HRPD/eHRPD) or LTE and/or GSM or LTE, e.g., using asingle shared radio. The shared radio may include a single antenna, ormay include multiple antennas (e.g., for MIMO) for performing wirelesscommunications. Alternatively, the UE 106 may include separate transmitand/or receive chains (e.g., including separate antennas and other radiocomponents) for each RAT with which it is configured to communicate. Asa further possibility, the UE 106 may include one or more radios whichare shared between multiple RATs, and one or more radios which are usedexclusively by a single wireless communication protocol. For example,the UE 106 might include a shared radio for communicating using eitherof LTE or 1×RTT (or LTE or GSM), and separate radios for communicatingusing each of Wi-Fi and Bluetooth. Other configurations are alsopossible.

FIG. 3 illustrates an exemplary, simplified portion of a wirelesscommunication system that may be particularly useful for implementingvoice or video over IP communication, such as voice over LTE (VoLTE) inan LTE network. As shown, the UE 106 may include an IP multimediasubsystem (IMS) client 306, e.g., which may be implemented in variousmanners, using hardware and/or software. For example, in one embodiment,software and/or hardware may implement an IMS stack that may providedesired IMS functionalities, e.g., including registration, AKAauthentication with IPSec support, session setup and resourcereservations, etc.

The UE 106 may be in communication with a base station, shown in thisexemplary embodiment as an eNodeB 102. In turn, the eNodeB may becoupled to a core network, shown in this exemplary embodiment as anevolved packet core (EPC) 100. As shown, the EPC 100 may includemobility management entity (MME) 322, home subscriber server (HSS) 324,and serving gateway (SGW) 326. The EPC 100 may include various otherdevices known to those skilled in the art as well.

The EPC 100 may be in communication with the IMS 350. The IMS 350 mayinclude call session control function (CSCF) 352, which may itselfinclude a proxy CSCF (P-CSCF), interrogating CSCF (I-CSCF), and servingCSCF (S-CSCF), as desired. The IMS 350 may also include media gatewaycontroller function (MGCF) 354 and IMS management gateway (IMS-MGW) 356.Similar to the EPC 100, the IMS 350 may include various other devicesknown to those skilled in the art as well.

Thus, the system of FIG. 3 illustrates an exemplary portion of the datapathway that may be used for voice or video over IP communication, e.g.,VoLTE.

FIG. 4—Exemplary Block Diagram of a UE

FIG. 4 illustrates an exemplary block diagram of a UE 106. In someembodiment, UE 106 is a device that has a limited link budget. As shown,the UE 106 may include a system on chip (SOC) 400, which may includeportions for various purposes. For example, as shown, the SOC 400 mayinclude processor(s) 402 which may execute program instructions for theUE 106 and display circuitry 404 which may perform graphics processingand provide display signals to the display 460. The processor(s) 402 mayalso be coupled to memory management unit (MMU) 440, which may beconfigured to receive addresses from the processor(s) 402 and translatethose addresses to locations in memory (e.g., memory 406, read onlymemory (ROM) 450, NAND flash memory 410) and/or to other circuits ordevices, such as the display circuitry 404, wireless communicationcircuitry 430 (also referred to as a “radio”), connector I/F 420, and/ordisplay 460. The MMU 440 may be configured to perform memory protectionand page table translation or set up. In some embodiments, the MMU 440may be included as a portion of the processor(s) 402.

As also shown, the SOC 400 may be coupled to various other circuits ofthe UE 106. For example, the UE 106 may include various types of memory(e.g., including NAND flash 410), a connector interface 420 (e.g., forcoupling to a computer system, dock, charging station, etc.), thedisplay 460, and wireless communication circuitry 430 (e.g., for LTE,CDMA2000, Bluetooth, WiFi, etc.).

As noted above, the UE 106 may be configured to communicate wirelesslyusing multiple wireless communication technologies. As further notedabove, in such instances, the wireless communication circuitry(radio(s)) 430 may include radio components which are shared betweenmultiple wireless communication technologies and/or radio componentswhich are configured exclusively for use according to a single wirelesscommunication technology. As shown, the UE device 106 may include atleast one antenna (and possibly multiple antennas, e.g., for MIMO and/orfor implementing different wireless communication technologies, amongvarious possibilities), for performing wireless communication withcellular base stations and/or other devices. For example, the UE device106 may use antenna 435 to perform the wireless communication.

As described herein, the UE 106 may include hardware and softwarecomponents for implementing features for communicating using one or morewireless communication technologies, such as those described herein. Theprocessor 402 of the UE device 106 may be configured to implement partor all of the features described herein, e.g., by executing programinstructions stored on a memory medium (e.g., a non-transitorycomputer-readable memory medium). Alternatively (or in addition),processor 402 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit). Alternatively (or in addition) theprocessor 402 of the UE device 106, in conjunction with one or more ofthe other components 400, 404, 406, 410, 420, 430, 435, 440, 450, 460may be configured to implement part or all of the features describedherein.

FIG. 5—Base Station

FIG. 5 illustrates an exemplary block diagram of a base station 102. Insome embodiments, base station 102 is configured to broadcast compressedSIBs usable by UE devices having limited link budgets. It is noted thatthe base station of FIG. 5 is merely one example of a possible basestation. As shown, the base station 102 may include processor(s) 504which may execute program instructions for the base station 102. Theprocessor(s) 504 may also be coupled to memory management unit (MMU)540, which may be configured to receive addresses from the processor(s)504 and translate those addresses to locations in memory (e.g., memory560 and read only memory (ROM) 550) or to other circuits or devices.

The base station 102 may include at least one network port 570. Thenetwork port 570 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106 (see FIG. 3),access to the telephone network as described above.

The network port 570 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 570may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

The base station 102 may include at least one antenna 534. The at leastone antenna 534 may be configured to operate as a wireless transceiverand may be further configured to communicate with UE devices 106 viaradio 530. The antenna 534 communicates with the radio 530 viacommunication chain 532. Communication chain 532 may be a receive chain,a transmit chain or both. The radio 530 may be configured to communicatevia various wireless communication technologies, including, but notlimited to, LTE, GSM, WCDMA, CDMA2000, etc.

The processor(s) 504 of the base station 102 may be configured toimplement part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 504 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof.

Overview of Compressed System Information

In one embodiment, UE 106 is a member of a class of UEs having limitedlink budgets. The limits may be based on the physical configuration ofUE 106, for example. In some embodiments, limited antenna gain of UE 106may reduce link budget, for example, based on antenna size orconfiguration. In some embodiments, UE 106 may include simplifiedreceivers, which may reduce costs but may also reduce link budget.Further, UE 106 may be a lower-power device, which may be advantageousfor various reasons but may also reduce link budget. In someembodiments, the status of UE 106 may change from a limited link budgetto a greater link budget, e.g., based on a change in battery level orlocation of the UE, for example. In other embodiments, UE 106 is alwayslink budget limited, e.g., based on the design of UE 106.

In some embodiments, UE 106 is a link budget limited UE configured tomake decision about threshold levels (e.g., for cellselection/reselection) without receiving information indicating thethreshold levels from base station 102. In other embodiments, UE 106 maybe configured with various types of information (e.g., as specified by adedicated server and/or stored as fixed constants, in some embodiments)rather than receiving the information in SIBs from base station 102.

Therefore, in some embodiments, the amount of system information neededby the class of UEs is reduced. Based on their limited link budgets,these UEs may have difficulty decoding traditional system information.Therefore, in some embodiments, base station 102 is configured tobroadcast compressed system information for the class of link budgetlimited UEs. In some embodiments, base station 102 is configured tobroadcast two types of system information: one type for the class oflink budget limited UEs and another type for other UEs. In variousembodiments, base station 102 is configured to transmit compressed SIBsat a lower coding rate and/or using smaller transport block sizes thannon-compressed SIBs.

The “coding rate” of a signal refers to a ratio between transport blocksize and the number of physical layer bits per subframe that areavailable for transmission of the transport block. A lower coding ratetypically means that more redundancy bits are inserted during channelcoding. In some LTE embodiments, coding rate is determined as (transportblock size+CRC bits)/(resource elements assigned to PDSCH/PUSCH*bits perresource element). Thus, smaller transport blocks typically correspondto a lower coding rate, assuming other variables (e.g., number ofresource elements and bits per resource element) remain constant.

In some LTE embodiments, system information is transmitted usingdifferent messages that include at least SIB type 1 (SIB1) messages andSI messages that can include one or more other SIBs (types 2-17). Inthese embodiments, the SIB1 message may be broadcast in subframe 5 witha periodicity of 80 ms. SIB1 may be repeated when the system framenumber (SFN) modulus 2=0. In this embodiment, a new SIB1 is sent every80 ms while, within the 80 ms period, the same SIB1 is repeated every 20ms. SIB1 may define the periodicities of the other SIBs. For example,the periodicities of other SIBs may be set to 8, 16, 32, 64, 128, 256,or 512 radio frames in one embodiment. In some embodiments, one or moreof the other SIBs may be grouped into a set of SI messages, e.g., forSIBs with similar schedules. The length of the SI windows for SImessages may be set to 1, 2, 5, 10, 20, or 40 ms, in some embodiments.Within an SI window, only one SI message may be sent, but it may berepeated multiple times. Thus, to acquire an SI message, a UE may beconfigured to monitor from the starting point of an SI window until theSI message is received.

In LTE embodiments that implement compressed SI, the compressed systeminformation may be periodically broadcast on broadcast control channels(BCCH). In some embodiments, the compressed SI is divided intocompressed SIBs, similarly to traditional SIBs. In these embodiments, atransport block may include one or more compressed SIBs. The size of thetransport blocks may be reduced, given the reduced amount of datapresent in compressed SIBs. In some embodiments, base station 102indicates that a transmission includes compressed SIBs using a dedicatedradio network temporary identifier (RNTI) which may be referred to as acompressed SI-RNTI (non-compressed SI broadcasts may be indicated usinga different SI-RNTI). In some embodiments, the compressed SI-RNTI isselected from among reserved RNTIs (e.g., 00×FFF4-0×FFFC in someembodiments). In these embodiments, compressed SIB1 may be periodicallytransmitted on a fixed schedule, similarly to traditional SIB1, andcompressed SIB1 may indicate scheduling of other compressed SIBs. Liketraditional SIBs, compressed SIBs with similar scheduling may becombined in a compressed SI message.

The coding rate and TB size for compressed SI messages may be determinedin order to allow decoding by a class of UEs based on their limited linkbudget. In some embodiments, base station 102 is configured to transmitcompressed SIBs using smaller TBs and/or a lower coding rate relative tonon-compressed SIBs. In some embodiments, a UE device may monitor forthe compressed SI-RNTI on PDCCH when expecting a broadcast within aspecified compressed SI message window or based on a chosen periodicityon a fixed subframe. The compressed SI-RNTI may be used to flag PDSCHtransmissions that include compressed SI messages (which in turn includeone or more compressed SIBs). In some embodiments, UEs having limitedlink budgets are configured not to monitor for the legacy SI-RNTI, i.e.not configured to decode legacy SIBs.

In some embodiments, the compressed SI-RNTI may be used to send varioustypes of proprietary configuration information to a UE. As onenon-limiting example, SIB2 traditionally includes information aboutphysical RACH configuration. However, an eNB and UE may agree on using adifferent RACH configuration for a particular set of devices and the eNBmay use the compressed SI-RNTI to send that configuration. Similartechniques may be used for various information included in SIBs. Thus,formats different than those specified by a telecommunications standardsuch as LTE may be implemented in various embodiments.

Exemplary Compressed SIBs

FIGS. 6A-6B show one embodiment of a compressed SIB1 message that hasbeen modified from a traditional SIB1 while FIGS. 7-11 show embodimentsof information elements (IEs) for compressed SIBs that have beenmodified from traditional SIBs set out in the 3GPP TS 36.331 V12.3.0standard. These compressed SIBs (other than compressed SIB1) may beincluded in a compressed SI message. The information is specified usingabstract syntax notation (ASN). As shown, information in dashed boxes inFIGS. 6A-10 is included in traditional SIBs as specified by 3GPP TS36.331 V12.3.0 but is not included in the compressed SIBs whileinformation in the solid box in FIG. 11 has been added to the compressedSIBs. In some embodiments, an eNB is configured to broadcast bothcompressed SIBs and traditional SIBs. The base station may transmit bothcompressed SI and non-compressed SI at the same time, in parallel. Forexample, in a given 80 ms period for a non-compressed SIB1, base station102 may also transmit one or more compressed SIB 1's, which may indicatescheduling for other compressed SIBs. Embodiments of traditional SIBsare specified in 3GPP TS 36.331 V12.3.0 (2014-09) at 6.2.2 and 6.3.1,for example.

FIGS. 6A-6B show information for one embodiment of a compressed SIB1message 600. (The information begins on FIG. 6A and continues on FIG.6B). In the illustrated embodiment, certain cell selection thresholdvalues in information 610, 620, 630, and 640 have been removed andmaximum uplink power information (p-Max) has been removed frominformation 610. Therefore, a compressed SIB1 message includes less datathan a traditional SIB1 message.

FIG. 7 shows information elements 700 for one embodiment of a compressedSIB type 2. In the illustrated embodiment, access class(ac)-barring-info has been removed from information 710, 730, and 750.In some embodiments at least a portion of this information is moved toSIB type 14, as shown in FIG. 11. This may reduce the size of SIB2 whilestill communicating sufficient information for the class of link budgetlimited UEs. In the illustrated embodiment, additionalSpectrumEmissionfields have been removed (information 720 and 740). In some embodiments,radioResourceConfigCommon for secondary cells will not be present as atmost one carrier is supported for the class of UEs. As shown, acompressed SIB2 includes only a portion of the data included in atraditional SIB2.

FIG. 8 shows information elements 800 for one embodiment of a compressedSIB type 3. In the illustrated embodiment, thresholds for cellreselection have been removed from information 810, 820, 830, and 840.In the illustrated embodiment, speed parameters have been removed(information 810 and 840). In the illustrated embodiment, certainpriority, bandwidth, neighbor cell information, and two-cell-antennainformation has been retained. As shown, a compressed SIB3 includes onlya portion of the data included in a traditional SIB3.

FIG. 9 shows information elements 900 for one embodiment of a compressedSIB type 4. In the illustrated embodiment, offset information 910related to selection thresholds has been removed. As shown, a compressedSIB4 includes only a portion of the data included in a traditional SIB4.

FIG. 10 shows information elements 1000 for one embodiment of acompressed SIB type 10. In the illustrated embodiment, informationrelated to cell selection thresholds, speed, and maximum uplink powerhas been removed from information 1010, 1020, 1030, 1040, and/or 1050.As shown, a compressed SIB10 includes only a portion of the dataincluded in a traditional SIB10.

FIG. 11 shows information elements 1100 for one embodiment of acompressed SIB type 14. In the illustrated embodiment, information 1110related to access-class-barring has been added to SIB type 14. In oneembodiment, this information is moved from SIB type 2 to SIB type 14 forcompressed SI messages.

In some embodiments, compressed SIBs for SIB types 6-8, 13, and 15 arenot implemented and these SIB types are simply dropped (i.e., notbroadcast) for the link budget limited class of UEs. In someembodiments, SIB types 10-12 and 16 are unchanged for the link budgetlimited class of UEs. Therefore, compressed SI messages may includetraditional SIB types 10-12 and 16.

Thus, in one embodiment, the following compressed SIBs may be utilized(the information listed for each is exemplary and intended to summarizethe purpose of each SIB but is not intended to limit the utility or typeof information corresponding to a given SIB):

SIB 1: cell access and SIB scheduling

SIB 2: resource configuration

SIB 3: cell re-selection info

SIB 4: intra-frequency cell re-selection

SIB 5: inter-frequency cell re-selection

SIB 9: home node B (HNB) names (for manual selection)

SIB 10: earthquake and tsunami warning system (ETWS) primarynotification

SIB 11: ETWS secondary notification

SIB 12: commercial mobile alert system (CMAS) notification

SIB 14: access class barring info

SIB 16: global positioning system (GPS) and coordinated universal time(UTC) info

The compressed SIBs represented by FIGS. 6A-11 are not intended to limitthe scope of the present disclosure. In some embodiments, greater orlesser amounts of information may be removed from traditional SIBs forcompressed SIBs. In other embodiments, various other types ofinformation and/or organization may be used for compressed SIBs,including system information for non-LTE embodiments. LTE-specificembodiments have been described for illustrative purposes, but are notintended to limit the scope of the present disclosure.

Exemplary Methods

FIG. 12 is a flow diagram illustrating one embodiment of a method 1200for broadcasting compressed SIBs. The method shown in FIG. 12 may beused in conjunction with any of the computer systems, devices, elements,or components disclosed herein, among other devices. In variousembodiments, some of the method elements shown may be performedconcurrently, in a different order than shown, or may be omitted.Additional method elements may also be performed as desired. Flow beginsat 1210.

At 1210, base station 102 broadcasts first SIBs encoded using a firstcoding rate and a first identifier. Base station 102 may broadcast thefirst SIBs using transport blocks having a first size. In someembodiments, the first SIBs are traditional SIBs, e.g., as specified by3GPP TS 36.331 V12.3.0. In some embodiments, the first identifier is aSI-RNTI.

At 1220, base station 102 broadcasts second SIBs encoded using a secondcoding rate and a second identifier. In this embodiment, the secondcoding rate is lower than the first coding rate. In this embodiment, thesecond SIBs include only a portion of the information included in thefirst SIBs. In some embodiments, the second identifier is a compressedSI-RNTI. Flow ends at 1220.

In some embodiments, base station 102 is configured to communicate withmultiple UEs, e.g., a first UE that initiates communications based onthe first SIBs and a second UE that initiates communication based on thesecond SIBs. The second UE may have a limited link budget. In someembodiments, information included in the first SIBs that is not includedin the second SIBs includes one or more of: cell selection parameters,cell reselection parameters, maximum power information, spectrumemission information, radio resource configuration information, or speedinformation. In some embodiments, the first SIBs include one or more SIBtypes that are not included in the second SIBs. In some embodiments,information specified by one type of SIB in the first SIBs is specifiedby a second type of SIB in the second SIBs.

FIG. 13 is a flow diagram illustrating one embodiment of a method 1300for receiving compressed SIBs. The method shown in FIG. 13 may be usedin conjunction with any of the computer systems, devices, elements, orcomponents disclosed herein, among other devices. In variousembodiments, some of the method elements shown may be performedconcurrently, in a different order than shown, or may be omitted.Additional method elements may also be performed as desired. Flow beginsat 1310.

At 1310, UE 106 receives compressed SIBs in a broadcast transmissionfrom a base station. In some embodiments, the compressed SIBs includeless data than non-compressed SIBs that the base station is alsoconfigured to broadcast. In some embodiments, the compressed SIBs aretransmitted using a lower coding rate and/or smaller transport blocksize relative to non-compressed SIBs that the base station is configuredto broadcast. In some embodiments, UE 106 is configured to monitor for acompressed SI-RNTI in order to receive the compressed SIBs.

At 1320, UE 106 decodes the compressed SIBs. This may involvedetermining various information shown in FIGS. 6A-11 that is not markedthrough, in some embodiments.

At 1330, UE 106 initiates communication with the base station based onaccess parameters specified by the decoded compressed systeminformation. Flow ends at 1330. Based on the compressed systeminformation, the UE may decide to camp on a cell, based on adetermination that the cell is suitable. Based on the compressed systeminformation, the UE may perform cell reselection. Based on thecompressed system information, the UE may perform neighbor celldetection and/or measurements.

In some embodiments, a first telecommunications standard (e.g., an LTEstandard or a 5G standard) specifies contents of non-compressed SIBs. Inthese embodiments, the compressed SIBs do not include at least a portionof the following information specified by the telecommunicationsstandard: cell selection parameters, cell reselection parameters,maximum power information, spectrum emission information, radio resourceconfiguration information, or speed information.

The location of the compressed SIBs and/or their periodicity in the timedomain may be similar to locations and/or periodicity of legacy SIBs, insome embodiments. For example, the compressed SIBs may use the samesystem frame numbers (SFN) and subframes as legacy SIBs. In otherembodiments, because compressed SIBs may be indicated using a reservedRNTI, for example, the location and/or periodicity of the compressedSIBs in the time domain may be outside of the legacy SI window and maybe pre-agreed or negotiated between network elements.

In some embodiments, an apparatus includes means for receivingcompressed system information blocks (SIBs) in a broadcast transmissionfrom a base station, where the base station is configured to broadcasttransmissions with both compressed system information and non-compressedSIBs. In some embodiments, the apparatus further includes means fordecoding the compressed SIBs from the broadcast transmission. In someembodiments, the apparatus further includes means for initiatingcommunication with the base station based on access parameters specifiedby the decoded compressed system information.

In some embodiments, any of various techniques described herein may beperformed based on a computer program with instructions for performingthe techniques, e.g., in response to execution of the instructions. Insome embodiments, a non-transitory computer-readable medium isconfigured to store such program instructions.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. An apparatus, comprising: one or more processorsconfigured to: broadcast a first set of system information blocks (SIBs)including a first SIB type 1 and first SIB type 2, wherein the first SIBtype 1 includes scheduling information for other SIBs in the first setof SIBs including the first SIB type 2, and wherein the first SIB type 1is transmitted periodically during a time interval according to a fixedschedule; broadcast a second set of SIBs including a second, differentSIB type 1 and second, different SIB type 2, wherein the second SIB type1 includes scheduling information for other SIBs in the second set ofSIBs including the second SIB type 2, and wherein the second SIB type 1is transmitted periodically during the time interval according to afixed schedule, wherein the second set of SIBs are usable by a class ofuser equipment devices (UEs) having a limited link budget; andcommunicate with first and second UEs, wherein initial communicationwith a first UE that is not in the class of UEs is based on the firstset of SIBs and initial communication with the second UE that is in theclass of UEs is based on the second set of SIBs.
 2. The apparatus ofclaim 1, wherein the second set of SIBs include at least one field in aSIB type that is not included in the same SIB type in the first set ofSIBs.
 3. The apparatus of claim 1, wherein the first set of SIBs includeat least one field in a SIB type that is not included in the same SIBtype in the second set of SIBs.
 4. The apparatus of claim 1, wherein adevice in the class of UEs is temporarily link budget limited due tocurrent communication conditions.
 5. The apparatus of claim 1, wherein adevice in the class of UEs is a low power device that is link budgetlimited due to one or more of: size, battery capabilities, transmitpower capability, or receive power capability.
 6. The apparatus of claim1, wherein the first set of SIBs includes one or more SIB types that arenot included in the second set of SIBs.
 7. The apparatus of claim 1,wherein the first SIB type 1 includes cell selection information that isnot included in the second SIB type
 1. 8. The apparatus of claim 1,wherein the first SIB type 2 includes barring information that is notincluded in the second SIB type
 2. 9. An apparatus, comprising: one ormore processors configured to: refrain from decoding a first set ofsystem information blocks (SIBs) transmitted by a base station,including a first SIB type 1 and first SIB type 2, wherein the first SIBtype 1 includes scheduling information for other SIBs in the first setof SIBs including the first SIB type 2, and wherein the first SIB type 1is transmitted periodically during a time interval according to a fixedschedule; decode a second set of SIBs transmitted by the base station,including a second, different SIB type 1 and second, different SIB type2, wherein the second SIB type 1 includes scheduling information forother SIBs in the second set of SIBs including the second SIB type 2,and wherein the second SIB type 1 is transmitted periodically during thetime interval according to a fixed schedule, wherein the second set ofSIBs are usable by a class of user equipment devices (UEs) having alimited link budget; and initiate communication with the base stationbased on information specified by the decoded second set of SIBs. 10.The apparatus of claim 9, wherein the apparatus further comprises: atleast one antenna; and at least one radio, wherein the one or moreprocessors are configured to control the at least one radio to performcellular communication using at least one radio access technology (RAT).11. The apparatus of claim 9, wherein the apparatus is configured todecode the second set of SIBs and note the first set of SIBs in responseto a temporary link budget limited status relating to currentcommunication conditions.
 12. The apparatus of claim 11, wherein theapparatus is configured to decode the first SIB type 1 and first SIBtype 2 in response to a chance in communication conditions.
 13. Theapparatus of claim 9, wherein the apparatus is a low power device thatis link budget limited due to one or more of: size, battery capability,transmit power capability, or receive power capability.
 14. Theapparatus of claim 9, wherein the second set of SIBs include at leastone field in a SIB type that is not included in the same SIB type in thefirst set of SIBs.
 15. A method, comprising: broadcasting, by a basestation, a first set of system information blocks (SIBs) including afirst SIB type 1 and first SIB type 2, wherein the first SIB type 1includes scheduling information for other SIBs in the first set of SIBsincluding the first SIB type 2, and wherein the first SIB type 1 istransmitted periodically during a time interval according to a fixedschedule; broadcasting, by the base station, a second set of SIBsincluding a second, different SIB type 1 and second, different SIB type2, wherein the second SIB type 1 includes scheduling information forother SIBs in the second set of SIBs including the second SIB type 2,and wherein the second SIB type 1 is transmitted periodically during thetime interval according to a fixed schedule, wherein the second set ofSIBs are usable by a class of user equipment devices (UEs) having alimited link budget; and communicating, by the base station, with firstand second UEs, wherein initial communication with a first UE that isnot in the class of UEs is based on the first set of SIBs and initialcommunication with the second UE that is in the class of UEs is based onthe second set of SIBs.
 16. The method of claim 15, wherein the secondset of SIBs include at least one field in a SIB type that is notincluded in the same SIB type in the first set of SIBs.
 17. The methodof claim 15, wherein the first set of SIBs include at least one field ina SIB type that is not included in the same SIB type in the second setof SIBs.
 18. The method of claim 15, wherein a device in the class ofUEs is a low power device that is link budget limited due to one or moreof: size, battery capabilities, transmit power capability, or receivepower capability.
 19. The method of claim 15, wherein the first set ofSIBs includes one or more SIB types that are not included in the secondset of SIBs.
 20. The method of claim 15, wherein the first SIB type 1includes cell selection information that is not included in the secondSIB type 1.